Engine start control device is known as a conventional technique, which is provided with an engine start switch for giving an instruction to start an engine mounted on a vehicle, and first and second control circuits which are fed with power from a power source mounted on the vehicle and control engine start when the engine start switch is turned on and the instruction to start the engine is given (see, e.g., JP 2006/118481).
The engine start switch is constructed from a momentary push button switch and is turned on by a push operation.